Workscope for NAS/NRC Twin Registry. During the period June 15, 1975, and June 14, 1976, the Contractor shall: Update the master data file for mortality and cause of death; Update zygosity classification using fingerprint scores, anthropometric data, and data on physical characteristics; Analyze data from master file to determine death rates and concordance of death from specific causes; Prepare reports summarizing the results of analysis; and Prepare and distribute a report to twins registered in the twin registry describing the research activities and results of the registry.